BREEDING HABITS OF BUTLER'S GARTER-SNAKE. 19 



placed together in a cage. The female was courted by the males 

 for five days before she appeared to be ready for copulation. 



The method of courtship is exactly as described 1 for T. sirtalis, 

 The male or males lie on or closely along side of the female, keep 

 up at intervals a spasmodic movement of the abdomen, and 

 endeavor to maintain a loop of the tail over that of the female 

 and to insert the posterior part of the body, ventral side up, 

 under hers. 



Early on the morning of April 15 five males were at the same 

 time endeavoring to copulate with the female, showing at once 

 that the sexual impulse was at its height and confirming the con- 

 clusion that the so-called snake piles are due to this impulse. 

 The exact moment of copulation was not observed but it was 

 within a few minutes of 12 noon. When one of the males had 

 succeeded in inserting one of its hemipeni the right in the 

 cloaca of the female the other males at once crawled away. 



The pair remained in coitu for two hours and fifteen minutes. 

 During that time the male endeavored to maintain a position 

 along the back or close to the side of the female and when in this 

 position kept up the abdominal movements, but the female moved 

 rather constantly about, dragging the male often at full length 

 behind her. Occasionally she rolled rapidly over and over as 

 many as ten times, turning the body of the male at the same time, 2 

 but this did not break the connection, confirming Cope's 3 state- 

 ment that the hemipenis cannot be withdrawn except by 

 invagination. 



When the act of copulation was completed the male was 

 removed and the female carefully cared for. She ate freely, was 

 fed as much as she would eat, and was little disturbed. Under 

 this treatment she remained in the best of health and on Sep- 

 tember 6, about 10 A.M., gave birth to thirteen young. This 

 makes the period of gestation almost exactly 144 days. 



It should be remarked that either the length of the period of 

 gestation varies, or the breeding season is of some length and 

 depends upon whether the spring is early or late, for the writer 



1 Ruthven, A. G., loc. cit., p. 178. 



2 More or less of this restlessness of the female may have been due to her being 

 in captivity. 



Cope, E. D., Kept. U. S. Nat. Mus., 1898 (1900), p. 701. 



